Air over earth
Libra treats a relationship as an exchange to be balanced and kept interesting. Taurus treats it as something acquired and then maintained. Both are Venus, and the elements pull the same planet in opposite directions.
Libra therefore wants discussion, variety and the sense of being chosen repeatedly. Taurus regards the matter as settled and finds the reopening of it faintly insulting. Where the pairing succeeds, Taurus supplies the physical security Libra rarely builds for itself and Libra keeps Taurus from letting the thing go stale.
Cardinal against fixed
Libra is cardinal and Taurus fixed, so one initiates and the other consolidates. This is not a bad structure. Libra proposes and Taurus, once persuaded, holds the arrangement without further prompting.
The trouble is the persuading. Fixed earth does not move for argument, however elegantly it is made, and Libra's method is entirely argument. Taurus responds to changed circumstances and to time, not to a well-reasoned case, and Libra can spend years making cases that were never going to work.
Venus in two conditions
The shared ruler is the interesting feature. Venus in air is social, aesthetic and interested in the other person's reaction. Venus in earth is sensory, slow and interested in what can be held.
Having the same planet on both sides means the relationship is largely governed by two Venus placements, and where those actually fall decides a great deal. Two Venus positions in compatible signs make this pairing very easy indeed; two at odds produce two people with the same instinct and no shared expression of it.
Where it grinds
Stubbornness on one side and indecision on the other, which is a poor combination. Libra will not commit to a position and Taurus will not leave one, so a disagreement stalls without ever becoming a proper argument.
The second friction is sociability. Libra needs people and Taurus needs quiet, and the negotiation about how a weekend is spent recurs indefinitely. Neither concedes on it, because for both of them it is a matter of basic comfort rather than preference.
Why the shared ruler proves little
Sun-sign compatibility describes a tendency in a population large enough to include almost every kind of person. Two people in this pairing may be very well matched or not matched at all, and the sign of the sun does not distinguish between those cases.
The two Venus placements are the first thing to look at here, given the rulership. After that the Moon for emotional need and Mars for how conflict is conducted. Those, taken from real charts, describe the couple rather than the category.
Questions people ask about this
Does sharing Venus make Libra and Taurus compatible?
It gives them similar taste. Venus in air wants exchange and Venus in earth wants permanence, so the shared ruler is expressed differently.
Why does Libra struggle to persuade Taurus?
Fixed earth does not move for argument. It moves for changed circumstances and for time, neither of which is Libra's method.
What is the recurring argument here?
How much social life the relationship contains. Both treat their preference as a basic comfort, so neither concedes.
Which placements matter most?
Both Venus positions first, because Venus rules both signs, then the Moon and Mars in each chart.